Recently, information processing devices are used in various systems. However, power consumption of an information processing device varies according to changes in a requested processing load and a processing state such that an application has a peak time. As such, in order to realize stable operation, power control in an information processing device is important. Particularly, in an information processing device such as a server device in which full-time operation is required, it is necessary to prevent server down due to power supply shortage.
As a technology to control power of an information processing device corresponding to the above-described situation, a technology called a power peak assist function, as shown in JP 2003-150281 A (Patent Document 1), has been known. In order to realize such a power peak assist function, first, a power supply device and a battery are provided as a power supply module. Then, in addition to power supply from the power supply device to the information processing device, the power used by the information processing device is assisted by power supply from the battery, by the power peak assist function.
Here, an example of the power peak assist function will be further described, specifically. First, in order to realize the power peak assist function, in addition to the power supply module described above, a peak assist control unit, which controls the amount of power supplied from the power supply device and the battery to the information processing device, is provided. The peak assist control unit extracts the residual amount of the battery from the power supply module, and based on the information, instructs the information processing device of permissible power consumption. Thereby, the information processing device is able to perform operation within the range of the instructed power consumption, and the power is supplied from the power supply device and the battery up to the power consumption value. Further, in the case where the residual amount of the battery is in short, the peak assist control device controls the information processing device to operate within the power value available only from the power supply device.
Patent Document 1: JP 2003-150281 A
In the peak assist function described above, an upper limit value of power available solely from the power supply device, namely a power supply device upper limit value, is fixedly set. However, if the power supply device upper limit value is set to a low value, the amount of power supplied from the power supply device is not enough, and opportunities of supplying power from the battery to the information processing device increase. In that case, the residual amount of the battery is reduced significantly, causing problems that the information processing device goes down due to battery shortage and that performance degradation is caused due to occurrence of power capping. Meanwhile, if the power supply device upper limit value is set to a high value, opportunities for supplying power from the battery are reduced, whereby advantages of the peak assist function are not taken. This causes a problem that the facilities will be wasted.